1. Field of the Invention
The present invention relates to a sintered body for high-hardness tools using cubic boron nitride (abbreviated as cBN hereinafter).
2. Description of the Prior Art
cBN has a hardness next to diamond, and its sintered bodies are used for various types of cutting tools.
As an example of cBN sintered bodies suitable for cutting tools, Japanese Patent Laid-Open Publication SHO 62-228450 discloses a sintered body which is obtained by sintering 65 to 75% by volume of cBN powder and the remaining part of a binder under a superhigh pressure, wherein the binder comprises 25 to 50% by weight of Al and carbide or carbide-nitride of Ti, and the sintered body obtained has good chip-off resistance in the intermittent cutting of hardened steels and other like processes.
Japanese Patent Laid-Open Publication HEI 3-170638 discloses a sintered body for high-hardness tools, which is obtained by sintering 45 to 75% by volume of cBN powder and the remaining part of a binder under a superhigh pressure, wherein the binder comprises 5 to 25% by weight of Al and the remaining part comprises at least one of the compounds represented by (Hf.sub.1-Z M.sub.Z)C (where M denotes an element belonging to IVa, Va or VIa group in the periodic table except Hf, and where 0.ltoreq.Z.ltoreq.0.3), and the sintered body obtained exhibits good abrasion and chip-off resistances in the processing of cast irons.